The present invention relates to a vehicle seat belt retractor, and more specifically to a seat belt retractor having a locking pawl which is moved into engagement with a ratchet wheel to block seat belt unwinding rotation of a spindle in response to unwinding of a predetermined amount of the seat belt from the spindle.
A known retractor having a locking pawl which is moved into engagement with a ratchet wheel to block unwinding rotation of a spindle in response to unwinding of a predetermined amount of a seat belt from the spindle is disclosed in U.S. Pat. No. 4,726,539. The retractor disclosed in this patent has a ring gear which is rotated during unwinding of the seat belt. A pair of tabs are formed on the outside of the ring gear. Upon extension of a predetermined amount of the seat belt, one of the tabs engages an arm on a mode switching lever to pivot the lever. Pivotal movement of the switching lever actuates an overcenter spring to move a locking pawl into engagement with a ratchet wheel to block rotation of the spindle in a seat belt unwinding direction. Upon winding of almost the entire length of the seat belt back onto the spindle, a second arm on the switching lever is engaged by a second tab connected with the ring gear. The second tab pivots the switching lever and actuates the overcenter spring to move the locking pawl out of engagement with the ratchet wheel.